Referring to FIG. 5, a transfer circuit disclosed in Japanese Laid-Open Patent Publication No. 9-247217 is described below. In FIG. 5, a conventional transfer circuit includes a transmission circuit 100, an attenuation circuit 200, a transmission line pair 300, and a receiving circuit 400.
The transmission circuit 100 generates, from a transmission signal that is fed to an input terminal Tin of the transmission circuit 100, complementary outputs a-a′ having complementary logic levels, and the transmission circuit 100 provides the complementary outputs a-a′ to the attenuation circuit 200.
The attenuation circuit 200 cuts off the received complementary outputs a-a′ at a given frequency, and then attenuates the amplitude of each output. Further, the attenuation circuit 200 eliminates common-mode noise from the complementary outputs a-a′ and outputs the complementary outputs a-a′, as complementary outputs b-b′, to the transmission line pair 300.
The complementary outputs b-b′ are inputted, as complementary outputs c-c′, to the receiving circuit 400, after having been transmitted through the transmission line pair 300. The receiving circuit 400 recovers a transmission signal from the received complementary outputs c-c′ and outputs the transmission signal from an output terminal Tout.
Such a transfer circuit prevents, in the attenuation circuit 200, external common-mode noise from being superimposed on the complementary outputs b-b′, by the combination of capacitances C2 and C3 and a balanced transmission T-type resistance attenuation circuit. Such a circuit, however, has a problem in that when common-mode noise is superimposed on the complementary outputs b-b′ at any point after the transmission line pair 300, the receiving circuit 400 incorrectly recovers a received differential signal due to the superimposed common-mode noise.
Accordingly, an object of the present invention is to provide a receiver which is capable of properly recovering a received differential signal by eliminating common-mode noise.